// let count: number;

// count = 123;

// 基础类型 null, undefined, symbol, boolean, void
const count: number = 123;
const teacherName: string = "Dell";

// 对象类型
const teacher: { name: string; age: number } = { name: "Dell", age: 18 };

const numbers: number[] = [1, 2, 3];

class Person {}

const dell: Person = new Person();

const getTotal: () => number = () => {
  return 123;
};
